Internal combustion engines that are used on agricultural equipment (e.g. mowers) are often exposed to air that contains a large quantity of foreign matter. During the normal operation of such engines, the engines draw in air for combustion and cooling purposes. Mesh screens are typically placed over the air intake port on such engines in order to try to reduce the amount of foreign matter which reaches the engine interior. The screens can be designed so as to rotate along with the engine cooling fan so as to fling foreign matter away from the screen as it nears the air intake.
Even when rotating screens are used, there can still be problems with respect to foreign matter entering the engine housing between the screen peripheral edge and the inlet edge. Clogging and premature engine wear can result. The art has tried to solve this problem by using fan housing pressure to create back pressure adjacent the seam (see e.g. U.S. Pat. No. 3,183,899). However, this approach wastes valuable engine cooling air (thus decreasing cooling efficiency).
Another attempt to solve this problem is described in U.S. Pat. No. 4,589,379. With this approach, an upstanding annular flange is provided on the top of the fan housing, and the screen periphery extends over the flange and has blade elements that are bent down outside of the flange. This assembly cuts up the grass as it enters. While this system reduces the problems involved in the entry of long grass, it still permits an undesirable amount of cut pieces to be drawn in by the engine fan.
It can therefore be seen that an improved engine intake screen assembly is desired.